Ischemic mitral regurgitation is a common clinical problem with important implications on morbidity and mortality. Currently, lack of understanding of the mechanistic basis of IMR hinders the development of a reliable surgical treatment. Mitral valve repair is effective, but the results are unpredictable, and prosthetic rings alter annular and leaflet dynamics. Leaflet extension has been used clinically with anecdotal success in reducing mitral regurgitation and leaflet dynamics. Leaflet extension has been used clinically with anecdotal success in reducing mitral regurgitation in patients with ischemic heart disease. It offers the theoretical advantages of augmenting leaflet co-adaptation without disrupting annular and subvalvular dynamics. The procedure has not been rigorously tested, however, to evaluate its mechanisms or efficacy. This grant proposes to investigate the effectiveness of mitral leaflet extension in presenting mitral regurgitation in an ovine model of acute ventricular ischemia. It will test the hypothesis that extension of the anterior leaflet of the mitral valve with a pericardial patch will increase the leaflet to annular area ratio and thereby ameliorate acute ischemic mitral regurgitation. Annular ans subvalvular dynamics will be compared to that in control animals. Markers will be implanted on the left ventricle, papillary dynamics will e compared to that in control animals. Markers will be implanted on the left ventricle, papillary muscles, mitral annulus, and mitral leaflets. Anterior mitral leaflet extension will e performed on the experimental group using autologous pericardium. Temporary balloon occlusion on the circumflex coronary artery induce ischemia and IMR. Three-dimensional marker tracking, transesophageal echo, and hemodynamic data will be recorded to measure annular and subvalvular dynamics and valve competence.